Question

Ex nr 19 va rog frumos

Answer 1

Răspuns:

Explicație pas cu pas:

(10x + 9)(10x + 7) + 1 = 100x^2 + 70x + 90x + 63 + 1 = 100x^2 + 160x + 64 =

= (10x + 8)^2

n = 10x + 8, numar natural

______________

x = 1; 19*17 + 1 = 324 = 18^2

x = 2; 29*27 + 1 = 784 = 28^2

x = 3; 39*37 + 1 = 1444 = 38^2

x = 4; 49*47 + 1 = 2304 = 48^2

x = 5; 59*57 + 1 = 3364 = 58^2

x = 6; 69*67 + 1 = 4624 = 68^2

x = 7; 79*77 + 1 = 6084 = 78^2

x = 8; 89*87 + 1 = 7744 = 88^2

x = 9; 99*97 + 1 = 9604 = 98^2